Safety device for sewing machines



A. R. WOOD SAFETY DEVICE FR SEWING lMACHINES 3 sheetsusheei 1 Filed May 1l. 1920 lll..

wiTNEsEs:

A'ITORNEY April 8 1924. 1,489,295

A. R. woon SAFETY, DEVICE FOR SEWING MACHINES Filed May 11. ,1920y s sheets-sheet 2 WITNESSg: INVENTOR Mw @M N; @Q4/MW April s, 1924. 1,489,295

A. R. woon SAFETY DEVICE FOR SEWING MACHINES 3 Sheets--Sh'eet 3 llh Il lim f 4 YAllll INVENTOR WITNESSES: v M @FM av/19 Patented pr. 8, 1924.

UNITED e STATES PATENT :,oFFica.

ALFRED R. WOOD, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR TO TI-IE SINGER MANU- FACTURING COMPAINY, OF ELIZABETH, NEW JERSEY, A CORPORATION OF NEW JERSEY.

SAFETY DEVICE FOR SEWING MACHINES.

application med my 11, 1920. smal No.r 380,505.

To all whom t may concern.'

Be it known that I, ALFRED R. VVooD, av

citizen of the United States, residing at Bridgeport, in the county ofFairfield and State of Connecticut, have invented certain .new and useful Improvements in Safety De- ,o vices for Sewing Machines, of which the following is a specification7 reference being had therein to the accompanying draw- 10 ings.

This inventionrelates to sewing machines, more particularly of the automatic type embodying stitch-forming mechanism and a work-clamp, with means for yrelatively moving them to sew a' group of stitches, and with a stop-motion device for arresting` the aetion of the machine at the completion of a group of stitches.

throat-plate and are `connected to the clampopening treadle lf the operator depresses the treadle at any time prior to the elevation of the needlefrom the work after the for-ik mation of the last stitch of a group, breakage of the needle is .almost certain to result. e?,

Furthermore a premature opening of the clamp will release thework before thepnal stitch is set, thereby `interfering withthe proper action of the stitch-forming mechanism which is essential to the production of first class work. `@perators intrying to obtain maximum .,profluction, are accustomed to depress the clamp-opening treadle at the instant the machine stops. Occasionally an operator` in anticipating the action of the stop-motion, depresses the treadle ai fraction of a second too soon, thereby throwing Machines of the above type are customarily provided with athreadl cutter for severing the sewing-thread at the the pull-off and threadfcutter blades laterally against the needle which'is on its last up-stroke and has not been raised clear of the work. y f

As a matter of fact, when the usual stopmotion device is tripped into action, the sewing needle is below the work and the main-shaft of the machine executes aphalfrevolution before its motion is nally arrested with` the needle clear of the work. Although the time which elapses between the tripping of the stop-motion and the actual stoppage of the machine is very short, it frequentlyhappens that an operator will depress the clamp and thread-cutter operating treadle during such period and will consequently dama-ge the machine or spoil kthe product. i y

The primary object of theipresent invention is toprovide a safety device for Ia sewing machine ofthe class described which will preventV the machine or its product being damagedby a premature actuation of the lthread-cutter, work-clamp, or other part which Vis customarilylactuated at the end of the sewing period. I, f

More specifically',v an object of the inventionjis to improve the ,machine shown in the said Allen Patent No. 885,310 by equipping it with `a safety devic'efwhich .will prevent the operator from lifting the work-clamp l until theI needle is lifted clear of the work on itslast ascent andthe machine has actually .come to rest. The invention also contemplates the yprovision of means yfor, preventing the starting of the machine while the clamp-opening and thread-cutter operating treadle is depressed`- y ToA the attainment' of the` ends in view, a safety device, preferably in form rof a shiftable stop or locking element, is positioned in the path of movement of an element of the clamp opening Kor thread f cutting mechanism. This element is preferablyv so connectedwith the `stop-motion device as to be automatically shifted to unlocking position after the Amachine uis brought to rest.

Stop-motion devices comnnonly embody an eccentric stoppingr cam which is formed with a stop-notchV into which a plunger car-` ried by a tilting stopfmotion lever is pro,- jected to arrest the action of the machine);

(said plunger having been first moved by said lever into a position within the range of action of the stopping-cam. In order to defer the shift of the lockingelement to unlocking position until after the needle has been raised clear of-the work and the machine has stopped, the final movement of the stop-motion plunger into the notch of the cam is, through suitable connections7 made use of to shift the locking device from locking to unlocking position. A connection is also provided between said stop-motion lever and said locking element to prevent movement ofsaid lever to running position while the locking element is in work-clamp unlocking position.

A more complete understanding of the invention may be had from the following detailed description taken in connection with the accompanying drawings in which Fig. 1 side elevation of a machine embodying the invention. Fig. 2 isa ho-rizontalsection through the bracket-arm Vstandard at an elevation aboyethe worlcclamp and machinebed. Fig. 3 is a bottom plan view of the machine. Fig. 4 is a fragmentary elevation of the present safety device and associated parts looking from the front end of the machine. Fig. 5 is a plan view of the locking element and associated parts `in the respective positions occupied duringV the sewing. Fig. 5a isa similar view at a time in the sewing period when the stopmotion has been tripped to Vstop the machine, but before such stoppage has actually been effected. lFig.A 6 is a similar View at the end Vof the sewing cycle, after the machine has actually been stopped. Fig. 7 is a detail perspective view o-f an actuating element which acts upon the locking element. Fig. 8 is adetail perspective view of the locking element, and Figs. 9 and 10 are views illustrating the cooperative action of the stop-motion plunger and stopping cam.

For the purposes of the present disclosure the invention is shown as embodied in a bnttonhole sewing machine constructed substantially in accordance with the 'disclosure of the said PatentNo. 885,310 and comprising a bed l. Standard 2, and an overhanging arm 3, terminating in the head 4 which carries the reciprocating and laterally vibrating needle 5. and the buttonhole-cutter 6. with the shuttle 7 to form stitches.

The work is clamped beneath the usual upper clamping-foot 8 pivotally carried at the forward ends of the arms 9 of the workclamping lever 1() which is pivotally supported at 11 upon the hinge-block 1l fixed to a lateral extension of the longitudinal slidesplate 12. The longitudinal slide-plate 12 is mountd in suitable guideways in thev transverse slideaplate 13 and each of such The needle 5 cooperates as usual plates is provided with the usual connection with the feed-cam 14 from which the respective longitudinal travelling and lateral shifting movements are derived.

The under-thread pull-off and cutter customarily comprise a slide-bar 15 mounted in suitable transverse guide-ways upon the under side of the. bed-plate 1 and herein shown as provided with an L-shaped springblade whose shank or stem 16 is attached to the bar 15 by means of screws 17 and -whose operative portion 18 is formed with a knife-edge adapted to contact yieldingly with the under side of the needle-throat of which the farther side of the needle-hole 19 forms with the same a cooperating mein-- ber in conjunction with which the knife acts in shearing off the lower thread close to the material. The shank 2O of the pulloff lever is pivoted by means of a. fulcrumscrew 21 to a fixed bracket 22 beneath the bed-plate and is provided intermediate its ends with a slot 23 entered by the shank of a screw 24 carried by the slide-bar 15. The contracted operative portion 25 of the pulloff lever is rounded upon its outer eX- tremity and provided in its edge with a recess 26 for engagement with the lower thread leading from the thread-case to the needle-hole 19. The slide-bar has at one end of it-s lower side a stud 27 embraced by the forked forward end of a lever 28 mounted upon a fulcrum screw 29 and having its opposite end also forked to embrace the spherical head of a lateral stud 3() carried by the lower end of an arm 31 depending from a sleeve 32 loosely mounted upon the rock shaft 33 and carrying also a lateral arm 34 to which is attached a chain 35 which may be connected with a'footor knee-lever within the convenient reach of the operator in charge of the machine.

As represented particularly inFigs. 1 and 2, the upper clamp member 8 is provided with the usual upper compound thread cutting and nipping blade 36 mounted upon the lower end of the vertical shaft 37 to which is fixed the crank-arm 38. The crank arm 38 is connected with one end of a rod 39 disposed in the direction of longitudinal movement of the work-V holder and supported intermediate its ends by the arm 40 which is supported by the upper clamping arm 10 and serves in conjunction with the fixed collar 41 upon the rod 39 as a stop to limit the endwise motion of the rod under the action of the spring 42 connected at onev end with the arm 40 and at the other end with a pin upon another fixed collar V42 upon the rod 39.A rllhe previously mentioned rock-shaft is made use of to control the necessary endwise movements of the rod 39 for actuating the compound nipping and cutting blade 36. The rock-shaft 33 is mounted in bearings provided therefor in a bracket 43 secured upon `the bracket-4 arm 2, said rock-shaft having fixed toits forward end a" lateral arm 44 carrying at its outer end a latch plate 45 pivotally mounted thereon by means of a screw pin 46 and carrying a lateral pin 47 engaged by the free end 'of a spring 48 having its fixed end' attachedto the arm'44 by means of a screw 49, whereby the inner `end of the latchplate k45 is yieldingly pressed against a lateral stop-pin 50 upon the arm 44 'and the latch-'plate is normally maintained in line with itsc'arrying arm and with therod 39.

l'The 4rear end of the rock-shaft 33 is providedwith a lateraly arm 51 having a cylindrical socket 52 which carries a longitudinally-movable 'pin `53, with a collar 54 intermediate its ends and between which and the inner end of a `pfvrforated screw-plug55y at the rearward end of the socket 52 is interposed a spring 56 for yieldingly maintain-y ing thepn 5,3 in its forward position forv engagementwith the ,topf of a Collar 57 fixed uponthe stop-motion plunger-rod 58 sur- .rounded by va spring 59 interposed between said collar57 `andfa bearing 6()y for the plunger-rod inthe tiltable stop-motion lever 61, whereby the plunger-'rod is pressed normally upward for operativeengagement with ythe stop-motion cam 62 mounted upon the hubof and having vthe usual yielding connection with the fixed pulley 63 `upo-n the main-shaft 64,' the stop-motiondevic'e herey in represented being that `of prior United States Patents Nos. 767,539 of August 16,

1904 and 806,231'of rDecember 5, 1905.

`Whenthelstop-motionllever 61 is tilted forwardlyV torunning position, as shown in dotted lines,"Fi`g. 1`,the upper end of the plunger-rod 58 is.. drawn out of the path of movement oflthecam 62 and itsiixed collar` 57 is withdrawn y,from*contact withthe pin 53. The belt-guiding finger 65 carried by the `lever lfmaintains thebelt upon the fixed .pulley 63 during rthe sewing. In the run-v ing position of theparts corresponding with the dotted 'linepositionjof the stop-motion lever, the arm r44 is'extended vtoward the axial line `of 4therod 39 andits latch-plate 45 rest-s yieldinglyagainst such rod by which it is temporarily disp-laced from its normal position; 'As "`the `workclamp moves forwardly with thenormal feeding movement communicated lto it by the feed-cam 14,\the rod 39 iscarried with'it and its end passes the latch-plate 45 which isthereby enabled to drop in behindit under the action of the spring 48. In the return feed movement of the work-clamp to initialv position for the stitching "of the second side o-f the buttonhole, the rod y39 is detained by the latchplate 45, while the upper thread-cuttercarrying shaft 37 continues its travel with `the clamp-member 8, whereby the angular rela-k,V

tion 'of theMcrank-arml38 androd39 is gradually changed and thus Acauses the compound cutting and nipping blade 36 to be slowly.

wardly the plunger-rod 58, Fig. 10, in performance of its usual braking action and tofinally spring upwardly again into the stop-notch 66. The lateral movementof the plunger-rod 58 produced by the throw of the lever 61 brings the collar 57 into engagement with the yielding pin 53, as reprelar 57 and permits the pin 53`to` spring forward over the same and to be lifted upwardly thereby when the plunger-rod is projected into the stop-notch 66.` The shaftl 33 is thus rocked andcauses the arm 44 with the latch-plate ,45' to be lifted out of line with the rod 39 and the latter is permit-V ted to move backwardly under the'action of the spring 42 to produce thek operative movement of the compound nipping and cutting blade 36 across the upper end of the needle-opening 19-through which the needlethreadextends from the workto vthe needle-l eye.

k'I he upper clamping foot -8 is preferably adapted to be lifted by means ofthe treadle operated mechanism for the lower threadcutter. Connected to the armA 34 by means of the screw-pinf66 is the upper end of a bar 67 the cylindrically-shapedend of which enters a guide-aperture in af plate'68 screwed to the bed 1.4 Secured to theibar 67 by means vof a screw 69` vwhich passes through a vertical slot 7 O in said bar isa bracket-piece 71 carrying a lateral roll 72`which isdis-` posed above the rearward extremity of the upper clamp-arm l0. y' A pullupon the chain 35 will depress the bar 67 and force the roll 72 `downwardly against the4 clamp-arm 10 thus tilting the latter to elevate the clamping-foot 8. yIn order to lock the lowery thread-cutter mechanism and upper clamping arm during the sewing, a stopfor locking element s is provided preferably in the form of a three-armed lever pivotally mounted by means of ascrewl73 upon the plate 68,.v During the sewing, one arm 74 of said lever is yieldingly positionedbelow a-collar 75 fixed to the'bar 67. This arm serves to lock` the bar 67 and arm 34 against depression by a pull upon the chain 35.

Another arm 76 of they stop element sicarries a pin 77 'which' entendsy upwardly l5 sented in Fig. 1, and the subsequent descent of i A' the plunger-rod carries downwardly the colroo through a slot 78 in the forward end of the link-bar 79 and is connected by means of a spring 8O to said link-bar. The link-bar 79 is connected at its rearward end to lthe stopmotion lever 61.

The third arm 81 of the stop-lever s is formed at its extremity with an undercut beveled face 82, Fig. 8,'with which cooperates the beveled face 83 formed on the leverlateral arm 91 carried by a collar 92 fixed I to theV rock-shaft 33. lVhile the machine is sewing, the stop 74 and link 79 occupy the 'relative positions shown in Fig.l 5, the spring 8O being under tension.

In the position of the parts shown in Figs.

l1 and 9, the machine has just finished the sewing and the needle is on its last up-stroke but is not clear of the work. The workclamp lifting and lower thread-cutter operating mechanism is locked by means of the Astop 74. The stop-motion lever has been tripped and has sprung to full lineor stopping position. The collar 57 has shifted the pin V53 endwise against the force of the spring 56. 'The link 79 has been shifted from the position shown in Fig. 5 to that shown in Fig. 5, the slot 78'permitting such movement of the link 79 without disturbing the position of the stop 74 beneath the collar 75.

During the last half-rotation of the mainshaft from the position shown in Fig. 9, the plunger-rod y58 is depressed and the pin 53 is projected over the collar 57. After the needle has been lifted clear of the work, and the main-shaft has completed its last revolution, the stop-notch 66 is brought into register with the plunger 58 which thereupon is projected into said stop-notch to lock the machine. This actionl causes the collar 57 to lift the pin 53 and rock the shaft 33, thus depressing the arm 91 and link 88 and causing the lever-plate 84 to be turned from the position shown in Fig. 5a to that shown in Fig. 6. During the latter part of this turning movement of the lever- Y pla-te 84, the beveled face 83 coacts with the similar face 82 on the arm 81 of the stop s to swing the latter, Figs. 5a andl 6, sufiiciently to remove the stop-arm 74 from its locking position beneath the collar 75. The slot 78 in the link 79 permits the stop 74 to be swung bythe lever-plate 84 to unlock the work-clamp. Therefore, the work-clamp and lower thread-cutter mechanisms are llocked during the sewing and are not unlocked until the plunger l58 has been projected fully into the stop-notch 66 and the machine finally brought to rest at the completion of the last revolution of the mainthereto tothe positions which they normally occupy during the sewing. Also, the link 79 is drawn to the right, Fig. 1, and restores the stop 74 to the position shown in Fig. 5. If an attempt is made to start the machine while the work-clamp is held open, the collar 75 will block the motion of the stop 74 toward the rod 67, and the link 79 and stopmotion lever 61 will not be permitted to move to starting or dotted line position, Fig. 1.

It will be seen that the present construction provides for any desired adjustment of the clamp-lifting roll 72 on the bar 67 so that the clamping foot 8 need only be lifted sufficiently to release the work while the lower-thread cutting mechanism receives a full actuation in order that the proper length of bobbin-thread may be pulled of for the ensuing sewing operation.

The invention is not to be understood as limited to the exact construction Shown and described as it is obviously susceptible of material modification both in the form and arrangement of its parts without departure from the invention. l

Having thus set forth the nature of the invention, what I claim herein is :e-

1. A sewing machine having, in combination, stitch-forming mechanism, a workclamp, a stop-motion device including a notched cam, a tilting stop-motion lever and a spring-pressed plunger carried by said lever and adapted to enter the notch in said cam to stop the machine, clamp-opening means, a stop-element for locking said clamp-opening means against operation while the machine is running, means connected to said plunger for shifting said stopelement to unlocking position, and a connection between said stop-element and said tilting lever for preventing movement of the latter t-o running position while the workclamp is open.

2. A sewing machine having, in combinaof its arms adapted to lock said clamp-opening means against operation while the machine is running, means connecting a second arm of said three-armed lever to said plunger whereby motion of the latter into the notch in said cam will shift said threearmed lever to unlocking position, and a connection between the third arm of said three-armed lever and said tilting stop-motion lever for preventing movement of the latter to running position While the Workclamp is open.

3. A sewing machine having, in combination, stitch-forming mechanism, a workclamp, a stop-motion device including a notched cam, a tilting stop-motion lever and a springgpressed plunger carried by said lever and adapted to enter the notch in said cam to stop the machine, manually operated mechanism for opening said work-clamp, a locking element for preventing operation of said manually operated mechanism, means connected to said plunger for controlling the position of said locking element, and a link connected at one end to said tilting stop-motion lever and at its other end having a limited yielding connection with said locking element.

4. A sewing machine having, in combination, stitch-forming mechanism, a Workclamp, a stop-motion device including a notched cam, a tilting stop-motion lever and a spring-pressed plunger carried by said lever and adapted to enter the notch in said cam to stop the machine, a rock-shaft connected to be operated by said plunger in entering the notch in said cam, a manually operated lever fulcrumed loosely on said rock-shaft, an endwise movable vertically disposed bar connected at its upper end to said manually operated lever, guiding means for the lower end of said bar, a lateral projection on said bar adapted to engage and open the worlrclamp, a stop adapted to engage said bar and prevent movement thereof to open the work-clamp, and means connected to said rock-shaft for moving said stop to ineffective position.

In testimony whereof I have signed my name to this specification.

ALFRED R. WOOD. 

